Department of Cellular and Structural Biology, UT Health Science Center at San Antonio, San Antonio, TX 78229, USA; Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, USP, 13635-900 Pirassununga SP, Brazil.
Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, USP, 13635-900 Pirassununga SP, Brazil.
Anim Reprod Sci. 2014 Mar;145(3-4):150-60. doi: 10.1016/j.anireprosci.2014.01.011. Epub 2014 Feb 1.
The aim of this brief review is to clarify the role of melatonin in the production and preservation of mammalian gametes and embryos. Melatonin is an indoleamine synthesized from tryptophan in the pineal gland and other organs that operates as a hypothalamic-pituitary-gonadal axis modulator and regulates the waxing and waning of seasonal reproductive competence in photoperiodic mammals. A major function of the melatonin rhythm is to transmit information about the length of the daily photoperiod to the circadian and circannual systems in order to provide time-of-day and time-of-year information, respectively, to the organism. Melatonin is also a powerful antioxidant and anti-apoptotic agent, which is due to its direct scavenging of toxic oxygen derivatives and its ability to reduce the formation of reactive species. Mammalian gametes and embryos are highly vulnerable to oxidative stress due to the presence of high lipid levels; during artificial breeding procedures, these structures are exposed to dramatic changes in the microenvironment, which have a direct bearing on their function and viability. Free radicals influence the balance between oxidation-reduction reactions, disturb the transbilayer-phospholipid asymmetry of the plasma membrane and enhance lipid peroxidation. Melatonin, due to its amphiphilic nature, is undoubtedly useful in tissues by protecting them from free radical-mediated oxidative damage and cellular death. The supplementation of melatonin to semen extender or culture medium significantly improves sperm viability, oocyte competence and blastocyst development in vitro.
本文旨在阐明褪黑素在哺乳动物配子和胚胎的产生和保存中的作用。褪黑素是一种由色氨酸在松果腺和其他器官中合成的吲哚胺，作为下丘脑-垂体-性腺轴的调节剂，调节光周期哺乳动物季节性生殖能力的兴衰。褪黑素节律的主要功能是将每日光周期的长度信息传递给昼夜节律和年节律系统，以便分别向生物体提供时间和时间信息。褪黑素还是一种强大的抗氧化剂和抗细胞凋亡剂，这是由于其直接清除有毒的氧衍生物，以及减少活性物质形成的能力。由于脂质水平高，哺乳动物配子和胚胎极易受到氧化应激的影响；在人工繁殖过程中，这些结构暴露在微环境的剧烈变化中，这直接影响它们的功能和活力。自由基影响氧化还原反应的平衡，破坏质膜的跨膜磷脂不对称性，并增强脂质过氧化。由于其两亲性质，褪黑素无疑在组织中有用，可保护它们免受自由基介导的氧化损伤和细胞死亡。在精液稀释液或培养基中补充褪黑素可显著提高体外精子活力、卵母细胞活力和囊胚发育。
